Apiston/cylinder device operating in a cycle with steam as the working fluid executes the following steps: ∙ saturated-vapor steam at 300 (psia) is heated at constant pressure to 900(°f). ∙ it then expands, reversibly and adiabatically, to the initial temperature of 417.35(°f). ∙ finally, the steam is compressed in a mechanically reversible, isothermal process to the initial state. what is the thermal efficiency of the cycle?